Plating process



April 14, 1953 J. F. voGT ET AL 2,635,075

PLATING PRocEss Filed Feb. 28. 1948 Patented pr. 14, Y1953 PLATING PROCESS John FQVogt and Russen J. Herbert, st. Louis, Mo., assignors to Knapp-Monarch Company, St. Louis, Mo., `a corporation of Delaware Application February 28, 1948, Serial No. 12,032

3 Claims.

This invention relates to a nickel plating process wherein an object after being plated in accordance with our process requires a minimum of i polishing and practically no bufng at all pro-` viding a Watts nickel bath containing coumarin (as disclosed in the Harshaw British Patent No. 622,761) is used.

One object of the invention is to provide a plating process whichvinvolves certain steps that permit'the nal plating of an object with a bright nickel-solution that adheres in a superior manner tothe object and does not subsequently blister as with ordinary processes, the use of our.

process'requiring less polishing and bufng than ordinary bright nickel plating providing a Watts nickel plating bath containing coumarin (as disclosed in the Harshaw British Patent No. 622,761) is used preceding bright nickel plating carried out according to the Harshaw Patents Nos. 2,029,386, 2,029,387, 2,125,229, 2,198,267, 2,198,268, 2,290,342, 2,238,661 or 2,326,999.

Anotherfobject is to provide a process involving the steps of nickel plating in a Watts nickel bath containing coumarin (as disclosed in the Harshaw British Patent No. 622,761) and bright nickel plating with an intermediate step wherein the Work is subjected to a few seconds of reverse current iiow and then to a somewhat longer period of current'flow in the normal (from anode to work) direction ina solution oi sodium cyanide and sodium carbonate, this particular step of the process resulting in elimination 'of blistering and reduction of the necessityfor polishing and bufng, which are required in connection with nickel plating in a Watts bath' containing coumarin but less so with bright nickel plating according to the above identified Harshaw United States patents, the step of subjecting the work to the sodium cyanide and sodium carbonate solution being the means to eliminate subsequent blistering and minimizing the polishing and bufling operations.

More speciflcally, it is our object to provide an intermediate step between nickel plating in a Watts bath containing coumarin and bright nickel plating according to the above identified Harshaw United States patents which deplates the rst layer of nickel plating for about two to ve seconds and then replates for approximately twenty seconds in a sodium cyanide-sodium carbonate solution wherein the proportions are approximately 5 to 1 to secure best results.

With these and other objects in view, our invention consists in the specific steps of the process hereinafter outlined whereby the objects are attained as will be evident from th following description,` pointed out in our claimsy and illustrated rin the laccompanying drawings'v wherein:

Figure 1 is a diagrammatic view of the iirst step of our process consisting of nickel plating.`

Figure 2 is asimilar diagrammatic view of the second step of our process consisting of deplat' ing.

Figure 3 is a similar diagrammatic -view of the third step of our process wherein the work is Figure 4 is a similar diagrammatic view of theI nal step of the process which consists of bright` nickel plating.

The process of bright nickel plating heretofore has involved substantially two steps. The rst step is to plate in a nickel solution and the second step is to plate in a bright nickel solution. Various solutions have been discovered and used for general commercial Work such as the plating of electrical appliances.

To improve upon the nickel plating process asv just described however we have devised an intermediate step between the nickel plating and thel bright nickel plating steps thereof and our particular process will now be described after a brief description as to how the first nickel plating step is accomplished.

In Figure 1 we illustrate a plating tank Il) having therein a plating solution l2 which -isv an@ ordinary nickel plating solution or a Watts bath f work I6. The usual nickel plating is then donev by energizing the circuit so that current flows' and nickel is deplated from theanode i4 and plated on the work I6, the direction of nickel flow being indicated by the arrow 22.

The next step in our plating process is to place the work I6 in a tank 24 containing a solution 26 of six to sixteen ounces of sodium cyanide (10 ounces being preferable), two to ten ounces of sodium carbonate (2 ounces being preferable) in one gallon of water. 0r, according to the metric system: 45 to 120 grams of sodium cyanide per liter of water, grams being preferred, together with from 15 to 75 grams of sodium carbonate per liter of water, 15 grams being preferred. Four to ten volts (6 volts preferred) current is then passed in a reverse direction through the solution 2li-that is the positive wire I8 is connected with work and the negative wire 20 is connected with the anode. The direction of flow is then from the Work toward the anode as indicated by the arrow 28.V The duration of flow of current is preferably from two to ive seconds.

The next step illustrated in Figure?, is to reverse the direction of the current by connecting the positive wire I8 to the anode I4 and the negative wire 20 to the work I6, the anode and work still being suspended in the solution 26 already referred to in connection with Figure 2. The direction of current flow will now be inthe normal or plating direction as indicated by the arrow 30. We have found that approximately twenty seconds is satisfactory for the duration of current flow in the replatirig direction.

After the third step in the process thework is rinsed in clear water andvk then suspended in another tank 32 having a solution 34 therein which is a bright nickel solution such as any of thev for flow of bright nickel in the proper directionthrough the solution {i4-that is from the anode;

to the` work.

The intermediate steps illustrated in Figures 2 and 3 eliminate the blistering which readily occurs when articles are plated without such intermediate step. We have indicated certain proportions for the solution 26 and certain voltages and timingfor the current ow but this can vary to some extent and still secure satisfactory results. Wehave howeverindicated what we have found to be the best proportions, voltages and timing.

The resulting product from ordinary nickeling and bright-nickeling is only fair. Our process involving the intermediate steps` illustrated in Figures 2 and 3 improves upon the former processes, as the resulting product does not blister and requires but a minimum of polishing and practically no buiing. A longer lasting surface is thereby provided for electrical appliances and the likewhen our method is used and the finished product is attained with much less manual work atthel factory in connection with handling of appliances involving the necessity of polishing and bufiing them to bring out the luster of the finish. With our process this work and the time consumed by it is reduced to a minimum so that many more articles per day can be produced by the same number of workmen.

Some changes may be practiced in the steps of our processwithout departing from the real spirit and purpose of our invention. Accordingly, it is our intention to cover by our claims such deviations from the steps specifically enumerated as may be reasonably included within their scope.

We claim as our invention:

1. A method of preparing an article for electrodeposition thereon of a coating of bright nickel, said method comprising making said article the cathode in a rst bath, thereafter making said article the anode for two to ve seconds in a second bath, said first bath being a Watts nickel bath containing coumarin and said second bath consisting essentially of from 45 to 120 grams of sodium cyanide and from 15 to 75 grams of sodium carbonate per liter of water, the voltage in said second bath being from 4 to 10, and thereafter reversing the current in said second bath to make said article the cathode at said voltage for about twenty seconds.

2. A method of preparing an article for electrovdeposition thereonV of a coating of bright nickel,

said method comprising making said article the cathode in a first bath,` thereafter making said article the anode for two to five seconds in a second bath; said first bath being a Watts nickel bath containing coumarin and said second bath4 consisting essentially of from 45 to 120 grams of sodium cyanide and from 15 to 75 grams of sodium carbonate per liter of water, the voltage in said second bath being from 4 to 10, thereafter reversing the current in said second bath to make said article the cathode in said voltage for about twenty seconds andthereafter rinsing said article with water.

3. A method of preparing an article for electrodeposition thereon of a coating of bright nickel, said method comprising making said article the cathode in a first bath, thereafter making said article the anode for two to ve seconds in a second bath, said rst bath being a Watts nickel bath containing coumarin and said second bath consisting essentially of about grams of sodium cyanide and about 15 grams of sodium carbonate per liter of Water, the. Voltage in said second bath being aboutl 6, thereafter reversingV the current in said second bath to make said article the cathode at said Voltage for about twenty seconds, and thereafter rinsing said article with water.

JOI-IN E'. VOGT. RUSSELL J. HERBERT.

References cited in theme of this patent UNITED sTATEs PATENTS Number Name Date 93,157 Adams Aug. 3, 1869 1,534,709 Holt Apr. 21, 1925 1,574,055 Pedersen Feb. 23, 1926 1,918,605 Jones July 18, 1933` 2,384,660 Ward Sept. 11, 1945 2,451,341 Jernstedt Oct. 12, 1948 2,470,775 Jernstedt etal. May 24, 1949 OTHER REFERENCES Metal Finishing, pages 68-72, 1947. 

1. A METHOD OF PREPARING AN ARTICLE FOR ELECTRODEPOSITION THEREON OF A COATING OF BRIGHT NICKEL, SAID METHOD COMPRISING MAKING SAID ARTICLE THE CATHODE IN A FIRST BATH, THEREAFTER MAKING SAID ARTICLE THE ANODE FOR TWO TO FIVE SECONDS IN A SECOND BATH, SAID FIRST BATH BEING A WATTS NICKEL BATH CONTAINING COUMARIN AND SAID SECOND BATH CONSISTING ESSENTIALLY OF FROM 45 TO 120 GRAMS OF SODIUM CYANIDE AND FROM 15 TO 75 GRAMS OF SO DIUM CARBONATE PER LITER OF WATER, THE VOLTAGE IN SAID SECOND BATH BEING FROM 4 TO 10 , AND THEREAFTER REVERSING THE CURRENT IN SAID SECOND BATH TO MAKE SAID ARTICLE THE CATHODE AT SAID VOLTAGE FOR ABOUT TWENTY SECONDS. 